Allow transitions to WebUI pages which are extension urls (new tab page is the relevant example).

content/public/common/page_transition_types.cc

Index: content/public/common/page_transition_types.cc
===================================================================
--- content/public/common/page_transition_types.cc	(revision 150475)
+++ content/public/common/page_transition_types.cc	(working copy)
@@ -42,6 +42,14 @@
   return type & PAGE_TRANSITION_QUALIFIER_MASK;
 }
 
+bool PageTransitionIsWebTriggerable(PageTransition type) {
+  int32 t = PageTransitionStripQualifier(type);
+  return (t == PAGE_TRANSITION_LINK ||
+          t == PAGE_TRANSITION_AUTO_SUBFRAME ||
+          t == PAGE_TRANSITION_MANUAL_SUBFRAME ||
+          t == PAGE_TRANSITION_FORM_SUBMIT);
+}
+
 const char* PageTransitionGetCoreTransitionString(PageTransition type) {
   switch (type & PAGE_TRANSITION_CORE_MASK) {
     case PAGE_TRANSITION_LINK: return "link";